Well cavity plug forming device



May 1, 1962 R. J. SMITH 3,032,115

WELL CAVITY PLUG FORMING DEVICE Filed Aug. 2, 1960 2 Sheets-Sheet 1 4 rroe/Vf YS.

R. J. SMITH WELL CAVITY PLUG FORMING DEVICE May 1, 1962 2 Sheets-Sheet 2 Filed Aug. 2, 1960 United States The present invention relates to a device for forming a plug in a well cavity.

In the drilling of an oil well, a drilling fluid or mud is circulated between the surface and the drill bit for the purpose of carrying to the surface the rock chips produced by the bit. Often the circulation fluid is lost by drilling into a cavity, room, or strata of fluid-pervious sand or soft rock into which the drilling fluid or mud flows and is lost.

An object of the present invention is to provide a device for forming a plug in a well cavity which lends itself to being drilled out after the cementitious material of the plug has set, the tube through which the cementitious material is introduced being fabricated wholly of plastic material, readily and with facility drilled through by the conventional well drill bit.

Another object of the present invention is to provide a well cavity plug forming device which lends itself to ready and quick assembly and attachment to the length of a well tube, one which is readily detached from the well tube when the plug has set within a cavity, one economical to manufacture and assemble, and one which is highly effective in action.

These and other objects and advantages of the present invention will be fully apparent from the following description when taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a view in section of a `well bore showing the device of the present invention in the process of being lowered in the bore to a position bridging `a cavity therein,

FIGURE 2 is a view of the well bore with the device of the present invention installed therein and cementitious material plugging the well cavity,

FIGURE 3 is a view on an enlarged scale of the device shown in cross section,

FIGURE 4 is a view taken on line 4-4 of FIGURE 3, and

FIGURE 5 is a view taken on line 5-5 of FIG- URE 3.

Referring in greater detail to the drawings in which like numerals indicate like parts throughout the several views, the reference numeral designates an oil well bore having a cavity 12 therein.

-The unit or device for forming a plug within the cavity 12 is designated generally by the reference numeral 14 and comprises an upstanding elongated, hollow openended tubular member 16 and a centering guide element 18 dependingly secured to the lower end of the tubular member 16.

The tubular member 16 and the guide element 18 are both fabricated wholly of a plastic material.

An upstanding ilexible, deflated elongated sac is circumposed .about the member 16, the sac being designated by the numeral 20. The sac 20 has the upper end gathered and sealingly secured to the tubular member 16 by means of a split ring 22. The sac 20 is impervious and loosely encompasses the member 16, and has a plurality of longitudinally-extending folds which extend from the upper to the lower ends. The sac 20 also has its lower end gathered and sealingly secured to the member 16 by another split ring 24.

The portion of the tubular member 16 adjacent the arent:

ICC

Z lower end immediately above the ring 24 is provided with a plurality of discharge passages 26 opening into the interior of the sac 20.

The upper end portion of the sac 20 is provided with a plurality of air pressure relief means in the form of flexible apertured nipples 28.

In use, the device 14 is attached to the lower end of a well pipe 30 by means of a resilient sleeve 32 having an inside diameter slightly less than the outside diameters of the pipe 30 and tubular member 16. After lowering the device 14 into the well bore 10 and positioning the sac 20 in the cavity 12, cementitious material, such as cement in unset condition is forced down the pipe 30 into the tubular member 16, and thence outwardly through the passages 26 into the sac 20 to expand the sac 20 laterally to provide a compartment several times the cross-sectional area of the member 16. Any air trapped in the upper end portion of the sac 20 escapes to the atmosphere through the nipples 28.

Upon the application of an upwardly directed force to the pipe 30, the pipe 30 will separate from the device 14 at the sleeve 32. When the cementitious material has fully set, the tubular member 16 and guide element 1S may be drilled out by the conventional drill bit and the bore 10 continued below the cavity 12, without being in communication with the cavity 12, thereby saving the circulation uid from loss into the cavity 12.

What is claimed is:

l. In a unit for forming a plug within anv oil well cavity, an opstanding elongated hollow open-ended mem-l ber, an upstanding flexible deflated elongated impervious sac circumposed about said member and having upper and lower ends sealingly secured to said member, said member adjacent the lower end being provided with discharge passages opening into the interior of said sac, and air pressure relief means embodying flexible apertured nipples in the upper end portion of said sac and opening to the atmosphere, said member being adapted to feed a cementitious material introduced into the upper end downwardly therethrough and into said sac through said passages and laterally expand said sac to provide a compartment several times the cross-sectional area of said member.

2. In a unit for forming a plug within an oil well cavity, an upstanding elongated hollow open-ended member fabricated wholly of plastic material, .an upstanding flexible deflated elongated impervious sac circumposed about said member and having upper and lower ends sealingly secured to said member, said member adjacent the lower end being provided with discharge passages opening into the interior of said sac, air pressure relief means in the upper end portion of said sac and opening to the atmosphere, and a centering guide element fabricated wholly of plastic material dependingly secured to the lower end of said member, said member being adapted to feed a cementitious material introduced into the upper end downwardly therethrough and into said sac through said passages and laterally expand said sac to provide a compartment several times the cross-sectional area of said member.

References Cited in the tile of this patent UNITED STATES PATENTS 1,523,286 Railsback Jan. 13, 1925 1,834,434 Starr Dec. 1, 1931 2,320,670 Scaramucci June 1, 1943 2,334,788 OLeary Nov. 23, 1943 2,629,446 Freling et al. Feb. 24, 1953 2,922,478 Maly Jan. 26, 1960 

